C-reactive protein at the interface between innate immunity and inflammation

Abstract

C-reactive protein (CRP), the prototypic acute-phase protein, increases rapidly in response to infection and inflammation. Although CRP was thought to be a passive, nonspecific marker of inflammation, recent studies indicate that CRP plays a key role in the innate immune system by recognizing pathogens and altered self determinants. Activation of complement and interaction with Fcgamma receptors by CRP provides a link between the innate and adaptive immune systems. Recent evidence suggests that CRP is a marker of atherosclerotic disease and may play a role in its induction. However, CRP has an anti-inflammatory role in autoimmune diseases, such as systemic lupus erythematosus. In this article, we review the biological mechanisms by which CRP exerts its effects on the immune system and discuss its role in infection, cardiovascular disease, malignancy and systemic lupus erythematosus.

Expression of C-Reactive Protein and Serum Amyloid A in Early to Late Manifestations of Lyme Disease

“…As a pattern recognition molecule, it binds a variety of ligands that are displayed on the surface of pathogens or become exposed during autologous cell stress, injury, or death [5]. Once bound, the effects of CRP can resemble some of the key properties of antibodies, including opsonin deposition and activation of the classical complement pathway, as well as direct interaction with phagocytic cells through Fcγ receptors [6]. Circulating CRP concentrations increase in response to many forms of infection, inflammation, tissue trauma, and malignancy.…”

“…Levels greater than 10 mg/L are recognized to indicate a clinically significant inflammatory state or "macro-inflammation", whereas levels of 3-10 mg/L are generally considered to represent "low-grade inflammation", possibly driven by mild cellular stress or injury [7,8]. Because CRP decreases rapidly following elimination of the stimulatory ligands, its measurement is considered to be a reliable indicator of acute infection and/or inflammation [5,6]. Serum amyloid A (SAA), an apolipoprotein associated with high-density lipoprotein particles, is another highly sensitive acute-phase reactant.…”

Single determination of C-reactive protein at the time of diagnosis predicts long-term outcome of patients with hepatocellular carcinoma

“…Following an acute phase stimulus, cytokines like interleukin (IL)-1 and IL-6 stimulate CRP production in hepatocytes, which is then released to the systemic circulation. 6 CRP binds to several ligands, is involved in opsonization, interacts and activates the complement system, and has an fragment crystallizable (Fc)c-receptor binding site. 7 Thus, CRP plays a key role in a wide range of inflammatory processes and provides a link between the innate and adaptive immune systems.…”

C - reactive protein: An inflammatory marker with specific role in physiology, pathology, and diagnosis

“…Baseline concentrations of CRP are influenced by many factors, including chronic microbial infections, smoking, BMI, coffee consumption, oral contraceptive use, and genetics. 57 Lifestyle factors, such as smoking and BMI, have a greater influence on baseline CRP levels than single nucleotide polymorphisms (SNPs), making the identification of a genetic association of CRP SNPs with cardiovascular diseases difficult. 59 The level of CRP is altered in variety of conditions; although the rise in CRP is non-specific, the quantum and the pattern of rise will help deduce the diagnosis.…”